In the recovery of metals, such as copper, in general, two techniques have been widely practiced. One is an open pit mining technique which is well known in the Western United States. Another is conventional underground mining techniques of various subcharacterizations. These two techniques tend to maximize the available ore recovery at the least expenditure of unnecessary energy. However, various constraints such as waste disposal problems have made these methods more expensive. Still further, increasing capital requirements and less rich ores make underground mining increasingly expensive. Moreover, it has become increasingly more difficult to be assured of an economic return when mining copper deposits by underground mining techniques, because the cost for sinking a shaft and developing the necessary tunnels to reach the available ore bodies have been increasing at a rate greater than a projected recovery of the metal. As a consequence, it has become increasingly harder to justify an investment in underground mining for the development of ore bodies. Still further, at the great depth at which metal ore bodies such as copper ore bodies are found or have been found and not yet exploited, it has become more costly to sink the necessary shaft and provide the tunnels to economically recover the metals, such as copper metal.
Still further, the recovery of the copper ore body by underground tunneling is subject to a further high risk, because the exact boundaries of the ore deposits have often not been ascertained with a degree of certainty which would provide assurance of the total recoverable potential of metal in the ore body.